1. Field of the Invention
The present invention relates to a purge system for substituting inert gas for the process gas remaining in a piping system in a semiconductor manufacturing process line and a purge joint provided in the purge system, more particularly to a purge system with a purge joint, whereby an effective purging work of process gas can be performed for a short time for replacement of devices connected in the semiconductor manufacturing process line.
2. Description of Related Art
There have conventionally been used high poisonous gases such as silane gas and the like for process gas in a device or chamber such as a chemical vapor deposition (CVD) device used in a semiconductor manufacturing line. The device is connected to a piping system for process gas in the line and needed to be detached for replacement or maintenance. In that case, the process gas remaining in the device must be replaced completely with inert gas when the device is detached. Therefore, the device is connected to a purge gas piping system for supplying inert gas.
FIG. 5 schematically shows a piping system in a conventional purge system. A device 101 such as a CVD device is connected with a piping system for supplying process gas and purge gas. In the piping system are installed a valve 105 and a joint 104. The joint 104 is connected to a purge gas supply source 110 via a valve 103 and a pressure regulation valve 102. The joint 104 is also connected to a process gas supply source 113 via a valve 112.
The device 101 is also connected with a piping system with an outlet port 111 for recovering process gas. In this piping system are arranged a joint 107 and a valve 106. The joint 107 is connected to the outlet port 111 via a valve 109, and also to a vent 114 for discharging the substituted gas through a valve 108.
In the above conventional purge system, the device 101 is exchanged in the following manner.
First, the valve 112 is closed to stop the flow of process gas and the valve 109 is closed to prevent the flow of the substituted gas to the outlet port 111. Then, the valves 103 and 108 are opened to allow purge gas such as nitrogen gas and the like to flow into the device 101, discharging the mixed gas of the process gas and the nitrogen gas through the vent 114. The substituted gas is discharged through the vent 114, not through the outlet port 111, in order to prevent the mixed gas including nitrogen gas from flowing in a process gas supply piping system. This is because there is a possibility that the mixed gas flowing in the supply piping system for process gas may cause the mixture of water or oxygen in the piping system, which may cause a problem.
The above system, however, has the following disadvantages. The amount of process gas used in the CVD device and the like is very small. The piping systems are so designed for allowing a small amount of gas to flow therein and therefore hard to allow a large amount of nitrogen gas to flow therein, so that it takes a long time to completely substitute nitrogen gas for process gas. This deteriorates a productive efficiency in the semiconductor manufacturing process.
To avoid the problem, a portable gas substitute device has been proposed in Japanese Patent publication No. 4-19899. If connected to a piping system, the gas substitute device can exhaust process gas and fill nitrogen gas in the piping system. More specifically, the device is provided with an exhaust pump, a substitute gas supply part, a pressure gauge, a gas sensor, a tank, and the like, which are mounted on a carriage so that the device is moved close to the piping system to be subjected to the substitution work of gas. Accordingly, this device can perform prompt gas exhaustion/filling for the piping system to be subjected to the substitution of gas. Having only one connecting portion to the piping system and the tank for storing exhaust gas, the device can be portable to enhance the operating efficiency as compared with the conventional processing system.
However, the above purge system disclosed in Japanese Patent publication No. 4-19899 has the disadvantages as below.
The publication disclosing no way of connecting the device, though it is movable, to the piping system to be subjected to the substitution work of gas. It seems that the device needs to be connected to the piping system every purging operation, which is extremely troublesome in operation. There is also a possibility that the rubbing between the device and a metallic pipe to be connected with the device produces particles. Such the particles will cause defects in recent semiconductors with high precision which strictly require the prevention of production of particles.